SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f58f8e12d94413fc6d6fa0e378fe335cb03f99c8aee172a3e10aee4f98082122' 
  AND token = 'y9jhmIj0aM7eLOqOe8ZatVgKbWu6qlCMnz/eSB/rKK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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