SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbc1730f871318b206d308bd00f84921c12f593e5acf67d7564c0a0a01edeb29' 
  AND token = 'B/WBPKhFTGC8z+3ZjFB3TDyEqUU8RHqdESHKYboHWvc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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