SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '17be4730795609a9261de17c4357c38dbc1756eb107744969d502ad15386f0b9' 
  AND token = 'ku4cg+qGged/jABlI1fZsJrhGkmKzge/uYGf1DQ4yhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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