SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9503a0d6b2983bf5a033827f3c3e411f20c3dd7844b9c136241cf4e6c769359' 
  AND token = 'Gz3B/9rV3R7v+qRDbBx7dqLbLCr9ZB/1Uxu+2h48LJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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