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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '81d6b79f5549c36900f38e12b63ddd972d39bbd475120115c67f27c10b00b26a' 
  AND token = 'x7zGpyl3lsm9IDXHidTNmYVn1Du9Bep4zRprA3VYqkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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