SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f6ce020590aa61e6dadf301c1cc29fa0d868883e139e9297c019b34a73aad2be' 
  AND token = 'rK/ItyspoSU6RuPUPCzsa4Gg+r6DHIRLNspmhCWXhxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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