SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31da8cc0afa70e6213be2c5e546f0031c6ba15deb9e8225e69ffe027e72fe8a5' 
  AND token = 'ymqgQn2VTjfvlQ3p7QBPhuxGqDsW/lBSXROkVu4lbAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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