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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a83992a5c1d6e82b738ad0a0e034b94313ed644469cb0a12c07a8ce93c1f1170' 
  AND token = 'ceNuf9F5CMfQQY5dmZm+SM4k6ajSk3uegvVkYE2wcHE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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