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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa99ad59d7073a7a5573920886b19b751add796e2f85ba2b8da45cfac1cff54c' 
  AND token = '84xLH/5fhSPWGimxPZjSOqI2dDiWPAFaQPFo+NX7zTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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