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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a3517a54eed8cc0e5d430f7a367e850978a7dfd192e9f0ca17a076e808c128a9' 
  AND token = 'Qn9YQ2nKZQBdnDv6Bcp/2j/K7sRWgx3S0mXlmFf60eE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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