SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a26068fc7cbd1b31844de0a8a76ce5c91fabc4903a449c30c27e7216bd23b067' 
  AND token = 'r4MxRGANub4+Qnb2cd9SriXcOrUpmOc31AEryV4dQTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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