SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9bc75ee2272bdc254f44987e75a70294e67b0a86edbae30e246ff1110288a7d' 
  AND token = 'duUtyingVoxaZor4QEW2cjhyH6mMeopqORKjNAve9Ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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