SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c862db5fd9eff1f9848f1928fa80d4a5791cd361d4614ab4e3c4abb8f0bed317' 
  AND token = 'QL5uqwqCQK/B0q7hubxFjmfOp+g6/QS/ro4Tm7lBL2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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