SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '63c987cbdf29d0dc9ec11268ae4f27a4492111b462d8dadc4e346b0c93363317' 
  AND token = 'pALSnFBjdK+QFERe/dvNaSIlTpfhc4NI8tEWjjB7Eyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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