SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6399378b86fad01b2d70d19309bf18507a683965a73bf4936da0b126ece0671' 
  AND token = 'WrDCGlxevcKbFpS947WEBlUzeZS9RbDcRtg8ny+RxAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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