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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4021c0b786b4439a8c7a3b541302e1908a7e8870c631b408141d61defa8abe2b' 
  AND token = 'uYsRTSSxNO3+CcZ6VUWrpvWvmx41aMWopzktXtEPV0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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