SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '136a4df609074f5da4347dbb08f086e75d2b8eb4deb153ce577f951582b435b1' 
  AND token = 'tmm6ZcmYJhxngKKC4tEsEqdHxN5A6UwY1PC5Dt8EGu4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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