SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b290887d4c7e482d8753244b4611fb50a12c19692b75a64b2be10b8737d598be' 
  AND token = '3/pE2VGIOJZsH/DKukD6j4JyvfGt5+RnOq7C5vT725Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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