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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2544612afa94081e7b7ba72f0a734965d3da6b23fa18364ff4122c2d9b57af78' 
  AND token = 'pVdOM0ydDEb+YXnWVf1dxNRSiFJelThcVowTyS+CTQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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