SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26d617453d906e332c790029104b98515348e23b20d96bbfdff57e37c196cd51' 
  AND token = 'nPhBo2/QFAeuiHG2rD+Urup6n2KWtz27ZvGndpZrGCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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