SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '206d17f9432b5180be2244b833493d5cf766f7af4984e643b0308a668f36be2e' 
  AND token = '4jZoJF4AWQidJAr/gp+mcN+4WSq5gGC8fIbcLzqu1Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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