SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b2b360e40b596916e768958213b15990f01a92a0e7886047929082375f0fe1be' 
  AND token = 'BPHmtx0SWNPtPDKYTwAbp8JZONS6YOWSFqe84zUQCIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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