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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71e0043df3765be3cc2bbe887abd5c4b5977237864d63a46204fcb2f41f4cc42' 
  AND token = 'O7TVx4jxqxiJlRDFoQhf2IntAFu+Sqj6cEBvMC1tWus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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