SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c743da2e21f3ee82acdd83a5d4f6d756566a699188c8bc1a08bfb6c3a58fa057' 
  AND token = 'qnPoMPNVn49O3leB1Rv2yYMZJAH3GGDI6OLhwQd/lTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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