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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '393ea78870edec3cd10912f8b76373da96a90d9727ebdda4ec6ab375dfc4a748' 
  AND token = 'MUglzOfCqaAitcjMT5P9P81YkoKWomLgifJpATv8WYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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