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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd503c5cd993f63175959cf4cc2a83f9192edb9db69da2d589f2ed28194e264ab' 
  AND token = '8OJ5fgGNBKJ1GxW5irxKta9BYZUB2/HwhLN55uwS9EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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