SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '975c58537efd509c3e1e3fb3ad6846efb0af2c0d0481b0813ec287350b44ae57' 
  AND token = 'HRhUYcNUUO3MmCRPTrbY4VGUSlweXaN65ztft+vgVQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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