SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af8f5fdb9cc23106874324bc2354fe6e9434e85da8750b9b48a002a50105dacd' 
  AND token = 'rPMoWKVy/LpFQwFWoJgzALs/qnM7+w9zJR7HUjXTXNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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