SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f375ccb276d6f30e7c20b765eb52c468e2639c96024152c07240ea262217d1d0' 
  AND token = 'aZGk1fjcuYKOC/7QRj8oWs27o1CxXaMuYCGIezZfHN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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