SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd02b2929374349116374f236e4843ba14563f8883d438fa079a8b012ecd89321' 
  AND token = 'slfeUVmwg1LpbxKkV0EkuKB264dbb/CHHr4tEAyWSaw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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