SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3f4928a62b4b6886b6983fad1573dd3628c21ac1150465db832ac21bfbe788b' 
  AND token = 'l/o5Kyc69ZjmLht+lOEOKottgCCqHs7wUMypvL78pvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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