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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9dd2f7316ede5e8530b1a2db7aff73df020fd897a080db213e0c8283c408dfc' 
  AND token = 'S+Uynh1pyibF2ECTphCFcnZFUIxTZDhGlz+4Ufb1Zkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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