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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '50b3c20768cbdd0ce5013aad3ca1069bc3cccfb98ca4226a5c3a749abba15c6a' 
  AND token = 'Rt/eokiUgORUwnJfDHOw1L/mg4tTYb1Irud48cwf7sE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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