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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe2be6a448f2ad1638e7013852ef7d29a00b46afae3e5f37ee02f36ef8f06dbb' 
  AND token = '6T2t8h3ocCc/Tpuzv0XM3VsbIMWqSYPMAPLf0/GCUVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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