SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b75fa292992930b1c47a89ae05bb98cb16a63361a80fa3294bb8f60bb1f85695' 
  AND token = 'ld7TONBf+BOzPk2mgkX1XCnns32+IQokRLGNlE+j/lY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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