SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75a7592e0398d27578795032cd43115ad71084309eceec7016effa618247fcdf' 
  AND token = 'Ahd6FfDsneCB/GcnYiGyXFrB4iHXssxDfrCCw9OTi1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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