SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efd10668de9824c194d51210d5d42c7afe282f0a4d488d6597c30335072aec45' 
  AND token = 'NirR6x0CEuyZTWwt7nIV5wGCh/IjGBdnNMZkc5MUEYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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