SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '984e809a1888a0eea7080266a92e20e134cf973c581773d0f20323a8f90e3bfb' 
  AND token = 'u2pWLTA+LNFT+KELmZzWgHlXVBcphXD+FWDKUMlYJww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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