SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c52acd71813b1d8efa1660abb74f226952b7de21d1fe0988eab180380351977' 
  AND token = 'c+eqwRW/Tq0t7cb/KzZ0uFuxX5W1wcnS0PdeKKmaVC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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