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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9273f673d60d4ecb646066556f0f42c242011e3442d7eeaeffe5e8b4764b8ab5' 
  AND token = '2IgfufCfwp6zaAO5byf86pZFplnSFBsUrWGYd/RYcbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}