SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1cf386db839869f14565173183dfb37efd5f8ca46515e580c7f848e949f6fb9' 
  AND token = 'Po54tZvnSrkcEnsTJvQFBBkwp31qybkqyCh5ZlEusdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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