SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc37f54d4ad23c7caa3046d6f7a605fd96454b0986927b46dd3dc76494a7ca97' 
  AND token = 'v7gc/BREB1VP+BZtDfPXVQyvUWD7DiYysmDi8jw3Zzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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