SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a74f0e15d09eb6806d3d105973018e517b68a48cbf5fd899b28be93d3a9c1adb' 
  AND token = 'FjGo+0Vz++vEb5ZKmQ4stB0oqSRK5xaxYwyq7y+N2Rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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